I debate that this is an entirely different question than was asked previously.
Any designer reasons that may have been cited for "why cap at +3" are valid responses for "what would change if the number was higher", assuming the designer reason was an intent to further some game design and not "just because".
Any response for &...
I think it's not worth it
It's probably most in keeping with the current approaches to questions on the stack, but (in this particular case) it seems like a solution which improves nothing beyond being conspicuously adherent to the currently dominant rules.
It's not really in question that
The original post was asking for something off-topic to the stack (...